"American ancestry" in the U.S. Census 
According to 2000 U.S census data, an increasing number of United States citizens identify simply as Americans on the question of ancestry. According to the United States Census Bureau, the number of people in the United States who reported American and no other ancestry increased from 12.4 million in 1990 to 20.2 million in 2000. This increase represents the largest numerical growth of any ethnic group in the United States during the 1990s. The US Census Bureau says, "Ancestry refers to a person’s ethnic origin or descent, 'roots,' or heritage, or the place of birth of the person or the person’s parents or ancestors before their arrival in the United States" American sociologist Mary C. Waters suggests that it may be speculated that mixed ethnicity or ancestry nominate a more recent and differentiated ethnic group.
|Plurality||AR KY TN WV|
|10%+||All but DE MD FL TX||IN MO|
|7.2%+||All but DE MD||IN MO OH||ME|
|Top 5||All but DE||IN MO OH
|CO ID OR
UT WA WY
In the 2000 United States Census, 7.2 percent of the American population chose to identify itself as having American ancestry (see Race and ethnicity in the United States for a list of ancestries in the U.S.). The four states in which a plurality of the population reported American ancestry are Arkansas (15.7%), Kentucky (20.7%), Tennessee (17.3%), and West Virginia (18.7%). Sizable percentages of the populations of Alabama (16.8%), Mississippi (14.0%), North Carolina (13.7%), South Carolina (13.7%), Georgia (13.3%), and Indiana (11.8%) also reported "American" ancestry. In the Southern United States as a whole 11.2% reported "American" ancestry, second only to African American. "American" was the 4th most common ancestry reported in the Midwest (6.5%) and West (4.1%). All Southern states except for Delaware and Maryland reported at or above the national average of 7.2% "American", but outside the South, only Missouri, Indiana, Ohio, Idaho, Maine. All Southern states except for Delaware, Maryland, Florida, and Texas reported 10% or more "American", but outside the South, only Missouri and Indiana did so. "American" was in the top 5 ancestries reported in all Southern states except for Delaware, in 4 Midwestern states bordering the South (Indiana, Kansas, Missouri, Ohio) as well as Iowa, and 6 Northwestern states (Colorado, Idaho, Oregon, Utah, Washington, Wyoming), but only one Northeastern state, Maine. The pattern of areas with high levels of "American" is similar to that of areas with high levels of not reporting any national ancestry.
2010 Census 
- Ancestry: 2000 2004, p. 6
- Reynolds Farley, 'The New Census Question about Ancestry: What Did It Tell Us?', Demography, Vol. 28, No. 3 (August 1991), pp. 414, 421.
- Stanley Lieberson and Lawrence Santi, 'The Use of Nativity Data to Estimate Ethnic Characteristics and Patterns', Social Science Research, Vol. 14, No. 1 (1985), pp. 44-6.
- Stanley Lieberson and Mary C. Waters, 'Ethnic Groups in Flux: The Changing Ethnic Responses of American Whites', Annals of the American Academy of Political and Social Science, Vol. 487, No. 79 (September 1986), pp. 82-86.
- Ancestry: 2000 2004, p. 7
- Ancestry: 2000 2004, p. 3
- Ancestry, U.S. Census Bureau.
- Waters, Mary C. (1990). Ethnic options: choosing identities in America. University of California Press. p. 36. ISBN 978-0-520-07083-7.
- http://www.census.gov/population/www/cen2000/censusatlas/pdf/9_Ancestry.pdf p. 155 (end)
- "B04006, People Reporting Ancestry". 2009-2011 American Community Survey. United States Census Bureau. Retrieved November 23, 2012.
- Morison, Samuel Eliot (1972). The Oxford History of the American People. New York City: Mentor. p. 216. ISBN 0-451-62600-1.